Visual comparator



L 1935- F. w. MACKENZIE VISUAL COMPARATOR Filed Dec. 28, 1931. 2 Sheets-Sheet l 44;, ATTORNEY Oct. 1, 1935- F. w. MACKENZIE VISUAL COMEARATOR File bec- 2 1931 2 Sheets-Sheet 2 Patented Oct. 1, 1935 UNITED STATES PATENT OFFICE Dayton, Ohio, a corporation of Ohio The Sheffield Machine and Tool Company,

Application December 28, 1931, Serial No. 583,499

2 Claims. (Cl. 33-147) This invention relates to new and useful improvements in visual comparators.

It is one of the principal objects of the invention to provide simple, accurate and eflicient means for gaging objects and amplifying their dimensions upon an illuminated indicator, such as a glass screen.

Another object of my invention is to provide on the free end of the indicator needle a glass target containing an engraved line impervious to light rays for projection in a magnified state upon a calibrated screen. Thus, by its position upon the screen, this target line, which varies in accordance with the dimension of the article being gaged, will indicate that dimension in a highly amplified manner without eye strain.

Due to the light weight of its moving parts and its simplicity of construction, my insti ument provides a speedy, reliable and accurate comparator having the capacity to constantly repeat the accurate measurement of a given standard or size block, and do so with great speed when operated by regular production help.

It is another object of my invention to provide a comparator which is readily adjustable for greater or less amplification.

Other important and incidental objects will be brought out in the following specification and particularly set forth in thesubjoined claims.

In the accompanying drawings illustrating my invention, Figure 1 is a front view of my complete visual comparator. Figure 2 is a schematic view in perspective of the amplifying means.

Figure 3 is a. sectional view taken through the indicator pivot mechanism on the center line thereof. Figure 4 is a detail view of the means for obtaining a' desired ratio of movement of the indicator needle with respect to the movement of its operating plunger. Figure 5 is a side view of the complete device. Figure 6 is a detail view of the clamping means for holding the comparator head in an adjusted position above the anvil. Figure 7 is a cross-sectional view of said clamping means, taken through the column on the'line I-'I of Figure 6. And Figure 8 is a focusing means for the objective mounting.

In a detailed description of my invention, the numeral I designates a base having an anvil supporting portion 2 and an oifset portion 3 containing a bore to receive a column 4. Vertically movable along the column 4 is a head 5.

The head 5 is preferably a one-piece casting formed as shown in Figures 1 and 5, with an inclined base portion 6, upwardly inclined webs I and 8, a front plunger bearing portion, a housing I for the optical system, and a central sleeve portion II which is slidable along the column 4.

Secured for rotation on the top portion of the neck 3 of the base I, is a bronze collar I2 formed with a slot to receive the lower end of a rack I3 that projects to the top of the column in close contact therewith. This collar is held in an adjusted position by a thumb screw I2. The rack I3 projects through a vertical slot I4 in an oflset portion of the sleeve II. 10

Rotatable in a reamed hole in the sleeve portion I I of the head 5, is a shaft I 5 carrying within the slot I4 a pinion I6 which engages the rack I3 to-elevate or lower the head when an-adjustment wheel I! on the end of the shaft is turned.

For the purpose of clamping the head 5 in an adjusted position upon the column 4, I have provided the following means. Referring to Figures 1 and 6, the numeral l8 designates a clamp stud which is screwed into a threaded hole in the sleeve II of the head 5 to carry an equalizer I9.

At its outer end the stud I8 carries a clamp wheel 20 that is counterbored to receive acompression spring 2I which exerts pressure on a washer 22. The spring 2| and washer 22 which surround the stud I 8, exert pressure on the equalizer I9 whose ends are recessed to press on the conical points 23, 23 of conical studs 24, 24 respectively. These studs 24, which are free to move in radial holes in the sleeve portion I I of the head 5, are formed with heels 25 that cause the pressure of arc portions 26 on them to be exerted against the column 4 to clamp the head 5 in an adjusted position upon it. The spring 2| permits the headto be raised or lowered on the column when the clamp wheel 20 is loosened a part of one turn and at the same time takes up all initial slackness of the various members of the unit.

Vertically movable in the bearing portion 9 of the head 5 is a plunger 21 whose lower end is directly above an anvil 28 mounted upon the anvil supporting portion 2 01 the base I.

At its upper end the bearing portion 9 terminates in an offset seat for an indicator needle supporting casting 29. The latter comprises a spacing block 30 integral with a plate 3| which projects above and a substantial distance to the left of it, there being secured to, its left side a spacing block 32 that is taller than the block 30. (See Figure 2.)

Fitted in a bore in the lower middle portion of the plate 3I is a race 33 containing ball bearings 34 for a journal 35 on one end of a pivot segment 36. On the other end of this segment there is a journal 31 which is received by ball bearings 38 in a race 39 fitted in a bore in the lower middle portion of a plate 40 which is correctly applied to the front faces of the blocks 30 and 32 by dowels 4i and 42 respectively. Holes 43 and 44 in the blocks 30 and 32 respectively register with similar holes in the plates to receive screws 45 for securing the plate unit to the upper web exten-.

sion 46 of the bearing portion 9 of the head 5.

Provided on the middle portion of the pivot segment 36 is a sector flange 41 to which the lower end of a needle 48, preferably constructed of aluminum is attached by fastening means such as rivets 49.

A variable contact in the form of the following means is interposed between the upper end 56 of the plunger and the fiat undersurface of the segment 36. Referring to Figures 2, 3 and 4, the numeral 5| designates a ball which is held between two flat springs, one spring 52 being fastened to the other spring 53 to clear a cylindrical holder slide 54 to which the latter spring is secured. At their outer ends these springs are formed with holes of less diameter than the ball justment is effected by a screw 55 which enters a threaded hole in the slide block 54 to which the inner end of the spring 53 is secured. Secured on the outer end of this screw is a thrust collar 56 which is received by a groove 51 in the bottom of a yoke 58 secured to the spacing block 32 to anchor the screw to the latter when the screw is turned.

By adjusting this screw 55, the degree of amplification of the indicator needle 48 can be varied for the same degree of upward movement of the work plunger, since the longitudinal movement of that screw will draw the contact ball 5| toward and away from the central axis of the pivot segment to which the needle is attached.

Secured to the upper end 50 of the work plunger 2'! is a collar 59, which is free to engage the lower edges of the plates 3| and 48 to prevent an upward travel of the plunger that would be so gisrtreme as to overload the ball bearings 34 and Secured to a projection on the lower part of the indicator needle 48 is a projection to which there is secured one end of a return or bias spring 60. The opposite end of this spring is attached to the web 46 at a point where it will always returnthe needle to a starting position and constantly maintain a load on the ball bearings in a direction of the thrust of the work plunger 21, thereby causing the instrument to register accurately with loose bearings.

For the purpose of raising the plunger 21 above the object to be gaged, various means may be employed. The means I have illustrated is a lever 6| which is pivotally secured within a boss 62 on the bearing portion 9 of the head 5. The inner end of this lever enters. a circumferential groove Secured in the front portion of an elongated hood 61 mounted on the top of the head 5 is a ground glass screen 68 upon which is inscribed a scale 69 which has calibrated tolerance limits for the dimensions of the article to be gaged.

For the purpose of projecting the magnified image 5 I preferably constructed of aluminum. At its upper end this cover is formed with an outwardly and downwardly projecting hollow head portion 12 15 containing a source of light such as the incandescent lamp 13. Mounted in the head'portion of the cover H between the lamp I3 and the target 64 is a condensing lens 14 for collecting the rays of light emitted by the filament 15 of the g0 lamp 13. (See Figures 1 and 2.)

Secured in the housing l8 immediately behind the target 64 is an adjustable projection objective 16 covered by the hood 61. The rays of light that pass through the target 64 from the g5 lamp 13 are focused into this objective and further magnified by a compensated eye-piece 11 positioned at the rear thereof.

Supported in the rear portion of the hood 6'! by a bracket 18 is a prism 19 which will reflect so" On the scale 69 of the screen 68 there are a plurality of vertical main division lines, indicated as 1'to 5, each of which representing .0001" of tolerance limits and extending in each direction from a central or zero point, each main division being divided into four parts representing 45v .000025". These divisions on the left 'of the zero point are indicated as minus, and on the right as plus, to designate undersize and average tolerance limits, respectively, for the dimensions being gaged. go

When an object to be gaged is placed in position between the anvil 28 and the plunger- 21, the needle 48 will be deflected so that the magnified image of the target line 66 will stop at a point on the graduated screen 68 that will indicate within 55 a millionth of an inch whether the dimension of the article is within the predetermined limits set by the standard gage block.

Having described my invention, I claim:

1. In an object gaging device of the type deco scribed, a support, an indicating member pivoted at one end to said support, a plunger between the object to be gaged and the said end of the pivoted indicating member for causing an amplified movement of said member corresponding to a 66 variation in the dimensionof the object, a ball, an adjustable slide in said support, and a flat spring secured at one end to said slide and formed at its other end with a hole of less diameter than the ball to hold the latter in an adjusted position 70 between the adjacent end of the plunger and the indicating member to vary the ratio of amplification of its movement to the plunger.

2. In an object 8 8 8 device of the Widescribed, a support, an indicating member pivoted "l5 a vertical cover for the indicating member, an

electric lamp on said cover in front 0! the target,

a condenser on said cover between thetarget and the lamp, to collect the rays of light emitted by lamp and iocus'them through the target, a

projection objective mounted on said support be hind the target, into which the rays of light are focused, a compensated eyepiece mounted on said support behind the objective to magnify said rays, and a prism mounted on said support behind the eyepiece to project the illuminated index .line upward and back upon the calibrated screen for the purpose specified.

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